Hibernate many-to-many cascading delete

Question

I have 3 tables in my database: Students, Courses and Students_Courses

Students can have multiple courses and courses can have

Answer 1

I found the correct mapping (and tested that with JUnit with an extensive case) in a similar scenario. I don't think I am going to post testing code because it would take long time to adapt to this example. Anyway the key is to:

• Not use mappedBy attribute for the annotations, use join columns
• List the possible CascadeTypes excluding REMOVE

In OP's example

@ManyToMany(fetch = FetchType.LAZY,
        cascade =
        {
                CascadeType.DETACH,
                CascadeType.MERGE,
                CascadeType.REFRESH,
                CascadeType.PERSIST
        },
        targetEntity = Course.class)
@JoinTable(name = "XTB_STUDENTS_COURSES",
        inverseJoinColumns = @JoinColumn(name = "COURSE_ID",
                nullable = false,
                updatable = false),
        joinColumns = @JoinColumn(name = "STUDENT_ID",
                nullable = false,
                updatable = false),
        foreignKey = @ForeignKey(ConstraintMode.CONSTRAINT),
        inverseForeignKey = @ForeignKey(ConstraintMode.CONSTRAINT))
private final Set courses = new HashSet<>();

@ManyToMany(fetch = FetchType.LAZY,
        cascade =
        {
                CascadeType.DETACH,
                CascadeType.MERGE,
                CascadeType.REFRESH,
                CascadeType.PERSIST
        },
        targetEntity = Student.class)
@JoinTable(name = "XTB_STUDENTS_COURSES",
        joinColumns = @JoinColumn(name = "COURSE_ID",
                nullable = false,
                updatable = false),
        inverseJoinColumns = @JoinColumn(name = "STUDENT_ID",
                nullable = false,
                updatable = false),
        foreignKey = @ForeignKey(ConstraintMode.CONSTRAINT),
        inverseForeignKey = @ForeignKey(ConstraintMode.CONSTRAINT))
private final Set students = new HashSet<>();

Extensive JUnit testing verified that:

• I can add courses to students and vice versa flawlessly
• If I remove a course from a student, the course is not deleted
• Vice versa
• If I remove a student, all courses are detached but they are still persisted (to other students) in database
• Vice versa